The condor's recovery shows that endangered species can be brought back from the extreme brink. And there are plenty of other examples.

Gray wolves, which by the 1970s were wiped out of most of their North American range due to hunting, have bounced back to more than 3,500, thanks largely to reintroduction efforts. Northern elephant seals, hunted down to fewer than a hundred individuals, now number 150,000 along the West Coast.

But with dozens of new species going extinct every day—scientists say that more than 20,000 plants and animals are on the brink of disappearing forever—deciding which species to save is a tricky question.

This week, National Geographic will spotlight some of the world's most innovative and unusual efforts to save disappearing species, from the mountains of Tanzania to the plains of Missouri, in a series called "Last of the Last."

The series will focus on campaigns to bring back species deemed worth saving. Which raises a basic question: How do we decide which species to save?

In some cases, scientists and economists use algorithms and logistical models to determine a return on investment for trying to save the last of the last: If x dollars are put toward saving the spotted owl, it's possible to determine how many might be saved.

In practice, though, scientists and conservations prioritize based on a mix of public perception and a species' economic value—for instance, whether it's a popular seafood or brings tourism dollars to a state.

And there's a another, more subjective factor: How they feel about a particular piece of flora or fauna.

"What we decide to save really is very arbitrary—it's much more often done for emotional or psychological or national reasons than would ever be made with a model," Sanjayan says.

As in the case of the condor, he says, "people end up saving what they want to save—it's as simple as that."

Some conservationists argue that how we choose which species live or die is deeply flawed, that our bias for preserving cute and fuzzy animals diverts precious resources from creatures that actually keep our planet humming.

Ants, for instance, are essential environmental helpers, distributing seeds, aerating soils, and eating other insects that are often human pests, says Marc Bekoff, an ethologist at the University of Colorado Boulder.

Hugh Possingham, an expert in environmental decision-making at Australia's University of Queensland, says our obsession with "celebrity species" is likely detrimental to as many as thousands of other creatures in need.

Snakes and Spiders Need Not Apply

Endangered species that get a lot of love are often those that elicit the broadest public interest.

Tigers are often rated the most popular animal in surveys conducted in the West, says Eric Dinerstein, lead scientist of World Wildlife Fund's (WWF) Conservation Science Program.

Elephants are another animal fan favorite, even though there are still a half a million left on Earth.

Many lesser known species of fish and frogs are in more dire straits, with just 20 individuals left in some cases, says Jean-Christophe Vie, deputy director of the International Union for Conservation of Nature (IUCN)'s Global Species Programme.

A bias against smaller, less iconic animals also shapes the decisions of major donors.

"If you want to attract the attention of companies, you are not going to achieve that with snakes and spiders," says Vie, whose new organization Save Our Species helps match funders with conservation groups that share their interests.

"Sometimes you want to save a species because you find it extraordinary and appealing—that's the way humans are."

Show Me the Money

Whether a threatened species has any economic value can go a long way in determining whether or not it disappears.

Murray Rudd, an environmental economist at Britain's University of York, recalls working for the Canadian government in the early 2000s, when Nova Scotia's Atlantic salmon population dropped precipitously and mysteriously to about 250 fish.

Government scientists decided to take the expensive step of capturing some of the fish and breeding them in captivity to prevent their local extinction and to keep their genes diverse and healthy. The cost likely ran into the millions of dollars.

But for many Canadians, the expense was worth it: A survey of 2,800 Canadian households revealed that most were willing to pay $86 a year (U.S. $81.21) to support conservation of Atlantic salmon.

Such reverence has made Atlantic salmon an important part of Canada's economy, even though Canada hasn't allowed commercial Atlantic salmon fishing since the 1990s (most of the Atlantic salmon people eat is raised on fish farms).

In 2010, Atlantic salmon was worth $255 million in gross domestic product and supported 3,872 full-time jobs or their equivalent, according to a report commissioned by the Atlantic Salmon Federation, a conservation group.

Those numbers encompass recreational fishing and fishing by Canada's native peoples, collectively called the First Nation; tourism; education; and spending by governments, universities, and nongovernmental organizations.

The report was commissioned to "bolster the business case for ongoing intensive efforts to protect wild Atlantic salmon," Rudd says, an effort that he called "completely legitimate."

"But does that sort of lobbying take away funds from other species?” he asks. "Almost certainly, given the government of Canada's sparse budgets and light interest in environmental resources that do not have direct industry relevance."

And Rudd says the Nova Scotia program was a futile effort, since Atlantic salmon in the southern edge of their range had dropped to such low numbers that they were never going to rebound.

"Everyone loves Atlantic salmon," he says, but "funding salmon conservation was taking a lot of money that could go to leatherback turtles, right whales, or [other] lesser known endangered species in that area."

"Common Sense" Conservation

Rudd is keenly aware of the politics around species revival. In 2011, he led a study that asked nearly 600 conservationists around the world big questions about saving endangered species—including how priorities should be set around which to save.

The study, published in the journal Conservation Biology, found that 54 percent of conservationists agreed that scientists need to set criteria for a controversial concept known as "conservation triage."

Such thinking holds that conservationists need to quickly decide which species can be saved while realizing that others, in Rudd's words, "can't be saved no matter how much money we pour into them."

The University of Queensland's Possingham supports a logistical model he helped develop to determine the cost-effectiveness of saving a species, which he says is "just common sense."

The method builds on other logistical models that assess a species' value and threats against it by including two previously ignored criteria: the cost of management and the likelihood that the management will succeed—that a species will be saved from extinction.

Possingham says the model, called Project Prioritization Protocol (PPP), showed that focusing on just a species' value and threats to it is inefficient and that considering other factors substantially increases the numbers of species that can be managed successfully.

That argument echoes a wildlife management approach known as "the ecosystem method," which involves setting aside species-rich regions, rather than trying to save a single species.

"If we protect vast swaths of habitats that have value to people," says Sanjayan, "we also pick up benefits to endangered species along the way."

That goes a long way toward solving conservationists' dilemma of what to save by trying to save a lot all at at once. As conservationists know all too well, he says, "it's bloody hard to pick and choose."

Want to continue the conversation? Ask conservationist Quentin Wheeler, @DeanWheeler, about how to save Earth's rare species during a Twitter chat on Friday, December 20, at 11:30 am ET. Follow Quentin and use #NatGeoLive to tweet questions.

I am a 4th grader and I
think we kids can do small things that help the environment in a big way.
Forests are being cut down because of families like ours buying forest wood for
furniture and flooring. People throw trash in the streets that later goes into
the ocean. Oil drips out of our cars that wind up in the ocean. Fish suffocate
in plastic bags that wind up in the ocean and animals choke on candy wrappers
and other litter. I agree with Mr. Sanjayan that it is important to save the
endangered animals’ habitat so that they can survive. I think that both adults
and kids can help endangered animals.

I would like kids to re-use
sandwich bags and tupperware for their school lunches. I would also like kids
to make cloth bags for the grocery store out of old t-shirts and old blankets
instead of using plastic bags. We kids could pick up trash and to make less
trash ourselves by re-using things. Also we kids could use less water for
little things like showers and brushing our teeth. We could talk our parents
into getting rid of our lawns and plant native plants in our yards.

If we kids
did little things like these, the Earth would be a great place for the animals
to live in. There would be more animals and fewer endangered species. There
also wouldn’t be as much trash in the roads, rivers, and ocean so that fish
would be plentiful again. The Colorado River would get bigger again and so
would other rivers and lakes.

I agree that adults can do big
things for endangered animals by preserving habitat, while we kids can do small
things for the animals and the planet would be much better off because of our
love for our home.

It is sad to come to the realization that the human race has been forced to decide whether or not to save an animal. we as humans should not have the responsibility to save these species but, we should have the urge to save these specie from extinction. The human race is the main cause of the destruction of these small ecosystems in which these essential species lived. Therefore, being the cause of their destruction it should urge us to save these animals.

Taking into account the efforts currently being made by conversationalists, i am pleased to see the amount of work put forth towards saving these species. Now the inevitable question rises again. Which animal do we save first? The idea of saving certain species related to the saving of another, gives hope to save large amounts of animals. like Christine Dell'Amore stated "By setting aside land for wide-ranging tigers, for instance, lots of smaller, lesser-known species—like pangolins, sloth bears, swamp deer, and pygmy hogs—will receive an umbrella of protection." These ideas can help save more animals, but it is extremely important that we remember that every animal in our ecosystem is important, each contributes to the well-being of another.

We have to start with biodiversity conservation at the ground level - literally. Soil microfauna is being destroyed by toxic agrofertilizers and pesticides worldwide. This goes into the food chain, which in turn affects everything, including humans. Healthy soils are a starting point. The other stupidity is thinking that we can save an animal if we don't first save its habitat. Numerous tree species are endangered, yet many NGO's run around trying to save cute cuddly animals, but never think about spending a red nickel on planting the trees those animals use for habitat. All of this is made worse by the fact that the general public is sitting around waiting for their governments to do something, not recognixzing their own responsibility to the planet. Democracies are a threat to the environment, because politicians operate between 4 year elections, so long term planning doesn't seem to offer them any short term gains. This is just a brief list of some of the practical, cultural, social and political challenges we have to tackle for any conservation program to be successful. How long will humans survive for once we have killed off the last pollinating insect?

conservation based on likes and dislikes, perception of profitability and exploitation, uses and demands will only lead to further degradation of the environment and the species within it by lowering the standard and following a subjective selective process. This will inevitably contribute to the negatives surrounding the horrors of human interference in the natural world over the recent time

The term "moral responsibility" doesn't sit right with me. It should be a moral URGE for us to help these animals, not a responsibility. The human race is essentially the reason why these animals' habitats have been destroyed. And now we look upon their survival with facts, figures and debate. Trying to salvage some of the mess greed and industrialization on Earth has created. We may be deemed the most intelligent on Earth, but we certainly aren't applying it. We should be using our intelligence to help these animals, to be creating an Earth where no animal should have to go extinct through means of the human's faults. Am I dreaming of another world?

The slope is too slippery to save many, and is getting steeper. Sad to note every one of the critters most desired to be saved are mammals like us. We see much of our mammalian selves in them. But that's not saving ecosystems that support these mammals, and us. That's what we don't save from ourselves, because the entire ecosystem doesn't look like us to us. So it dies, as it globally is. We're finished as well for the same set of reasons, we just don't know it yet.

Good article Christine. It covers a vital question and one which my LinkedIn group Biodiversity Professionals has frequently discussed.

The idea of triage is anathema to some conservation scientists who believe that accepting the extinction of just one species, whatever the justification via mathematical modelling, is the slippery slope. Could it come to a choice between the cheetah or lion, or rhino or elephant? Perhaps not, but an argument could be made that this abstraction of life's value reduces decisions to mere equations. Fundraisers will certainly be reluctant to let go of the emotional impact of a cuddly doe-eyed animal. To my mind, conservation is a balance between the emotional connection we have to nature (E. O. Wilson's "biophilia") and pragmatic dollars and sense.

Talking of dollars and sense, a related topic here is the egregious over-spending of some large conservation organizations who spend more time and effort perpetuating their bureaucracies than actual muddy boots field conservation. For all the hand-wringing and boatloads of money thrown at conservation over the years, one would hope some progress would have been made - but precious little in reality. Just Google the word "greenwashing" and you'll see what I mean, but that's a topic for another blog post, if you dare!

We should try to save the species that benefit us the most. Like it or not, we ARE the dominant species. And survival of the fittest means that we should work for our OWN benefit first. It isn't as if lions worry about hunting other animals to extinction. Sharks don't care how many of a particular species of fish are left when they choose to eat one.

I don't care how rare something is, if it is not useful, it is not all that valuable. Anyone who has ever watched Pawn Stars knows that just because something is rare doesn't make it valuable.

And anything that is going extinct for reasons OTHER than humans should be automatically last on the list, unless they are extremely valuable to humans. In those cases, we are tampering with evolution. Like Jeff Goldblum says in Jurassic Park, dinosaurs (or in this case, other species) had their chance and were selected to die out.

I appreciate that what the article is saying about having to pick which species are worth saving but I think there are a lot of benefits from saving the cute and cuddly mammals.

Many conservation organisations will highlight the plight of a tiger or an elephant for two reasons.

Firstly, these cute animals can be used as a bit of a cash cow for conservation organisations. What's going to raise the most money for conservation projects? An elephant or a goliath spider? I don't think many people will disagree that conservation charities shouldn't try to raise as much money as possible for conservation.

Secondly, many of these cute and cuddly species can either be classed as either umbrella species or keystone species.

African elephants can be classed as a keystone species because many of the ecological and behavioural traits help to maintain the ecosystem requirements for many other species. So, funding elephant conservation projects in turn helps to conserve many other species.

Umbrella species also does a similar thing but the species in question may not has as much of an impact on other species ecological niches. Tigers, for instance, can be used as a conservation umbrella species. So people want to conserve, protect and enhance tiger populations. How do we do that? We first conserve their habitat. Then we conserve their prey species. In return, every other species that has a similar habitat as the tiger we are trying to save, will benefit from the conservation project and funding.

With that in mind, maybe we don't have as many choices to make when it comes to which species to save.

IT is not just furry and cute...it is also the fact that if one TYPE of frog or snake or ant disappears, it will not be as big a deal as if the ENTIRE species goes extinct. I'm sure if there were just 20 frogs left in the world, we would try to save them.

If we know that this is happening, why don't we emerge to it? They call dogs a "man's best friend", but even they can become extinct. It's just too bad that we are still trying to kill and hunt these animals. Yes, some are considered as food to us like chicken and lobster, but once these animals are extinct, they wont be there to eat and hunt for. Once those kinds of animals are extinct and we wont be able to have them as a delicacy, we'll feel guilty because we have killed that whole species and we will no longer get to eat it. So people of the world, stop this nonsense and start saving, not killing animals and doing this will save humanity, so come on and don't let animals become extinct, which is 3/4ths our/humans fault. (Written by my daughter, Age 9

The dangerous aspect of all these articles coming out about this issue
now, is that the media, ahem, and conservation biologists, are letting people believe that we have to make
choices, that we are going to continue to trash the planet so we have to
choose which species get to survive - NOT that we have to get our crap
together because this is not our planet to trash and not our right to
commit this level of genocide. The size of our population and our greed are the problem, if we can't compose ourselves to have that much self control, very few of the other animals will survive us and then we will follow them in demise.

Lions, tigers and bears! I'm choosing predators, and here's why: post-Climate civilization will need women to keep the peace. Women can learn leadership by identifying with predators and - like the rangers at Gir, India - training to be intermediaries between humans and animals who would kill them.

"Fanged Wilds and Women Program" aims to engage ladies with the "ecology of fear," for the good of ALL species. Please see our website and help grow this idea!

@Abe Bob Really? You're a 4th grader? So you must be around 9-10 years old, right? I am truly amazed at how smart and articulate you are! WOW!

You
make some very good points, and you put a lot of adults to shame with
your intelligence! I hope you become a respected and well known
scientist when you're older! The world desperately needs talented people
like you!

well said ,, i agree with you,,, it just that everyone is deceived by that curtain of economics and personal provincial gains that they base their judgements solely on profitability....its ridiculous and sad

@Roger Harris The art has never progressed to changing the global human culture that is driving these extinctions. The fact that a species can be saved temporarily but not permanently is due to the fact the underlying conditions of extinction, our behavior, is not being addressed, let alone changed.

@John Kalawak Sadly, the net of life can't be in tatters with only certain strands saved "to benefit us", and keep us from extinction ourselves. It requires the entire ecosystem that thrived with humanity for well over a million years. Our experiment in modern living and has produced a complete and deadly failure to ourselves. As the last people will see, soon.

@John Kalawak That's a little short sighted. Yep, many species have declined and become extinct for non human reasons.

But with the amount of pollution we put out into the environment and the amount of changes humans have made to the landscape through farming, mining and fishing, there aren't many species or habitats that we haven't affected for the worse.

Aside from the moral reasons to conserve and protect species, protecting them can have a positive effect on human health.

The environment and plant and animal species have been proven to provide benefits to people through exercise, health, education etc. There are many studies on the links between the environment and human health. I think you should look into them before expressing the opinion you have.

Also, the decline of species can provide a measure for the health of the environment. Don't forget that plants and animals need clean air, clean soils and clean water to survive, just like we do.

If species are declining, we have to ask, is it because the environment is damaged and how will that affect us?

Declining species can tell us that there may be something wrong with the environment that we really on for our own survival.

We don't fully understand what each and every species contributes to the ecosystem. If we lose a species, we may find that it played a crucial role in supporting us and other species. I think the best example is Bees as pollinators. Bees pollinate the crops we eat, so without them (and other pollinators), we wouldn't survive.

It's interesting that you point out that lions don't worry about hunting other species to extinction. It's interesting because, in Britain we have no large mammal predators left. This is because we hunted all the wolfs to extinction. Being an island nation, we haven't the luxury of large predators from Europe migrating to us.

The effect this has had is an explosion in the populations of various species of Deer. Now Deer seem to be very harmless. They are until you remove their main predator, in Britain this was the Wolf.

The effect this has had on the British landscape is terrible. Deer population shave over grazed farm land which effects the farmers economic growth. The Deer also will eat saplings and eat the bark of young trees. This and the over grazing of farm land prevents rejuvenation of the natural environment and harms the habitats of other species.

I suppose what I'm trying to explain, is that there is always a consequence to losing a species. We just may not notice it in our day to day lives.

@Rick Toner Several conservationists agree with you that we should save the rarest and the most ecologically valuable species. But what we should and what we do are two very different things—a lot of species are saved because we like them.

@Sarah Bexell Solid points that hit an iceberg when you mention our over population. The problem isn't long term but short term, right now we have too many people and too much progress to allow the natural world to survive intact. Unless you can erase a couple of billion men today you are talking about an impossibility. We are in a bottleneck for all species. Whatever we do long range the bottle neck will continue for a while. During this bottle neck the natural world will need all the help it can get from proactive mankind or we will come out of this bottleneck in a century or two to a fauna and flora impoverished world. We have to actively protect what we can now so that in the future what we save will flourish again when our numbers are fewer. In the longer term your points are of course self evident.

@Christa Witvrouwen No, we aren't. Not for most of them. IF you think that humans are the cause of the near extinction levels for all..or even MOST...of the 20,000 species near extinction, you are a fool.

@Christine Dell'Amore I think we like mammals because they are more similar to us, so we empathize more easily with them, and understand them better, through similar expressions of emotion. It's really hard to look at a crocodile or an ant and have any idea how it feels, but a wolf shows in its face, posture, and behavior, similar reactions to ours.

You can see that reflected in the ranking diagram above: very humanlike apes at the top, very social and emotional elephants next, cats like those we live with after that.

There's also the societal similarities that a lot of mammals have, namely in relationships with and behavior towards mates and offspring, which we can recognize and identify with more easily.

There's also the impact of litter sizes. Big mammals and birds tend to have few offspring at a time, which makes each one seem very precious. Reptiles, fish, and insects can have hundreds to thousands at a go.

It's like inflation or supply and demand. The "emotional" decision-making is in some ways a natural and internalized "conservation triage" that helps us see where our efforts will have the greatest relative impact. If we get down to just a few elephants, it's going to take centuries for there to be many elephants again. If we get down to a few ants, we could have millions again within a few months.

And as Sanjayan said, when we actively protect one animal and its environment, all the others benefit. I think we deeply already understand this, and it's internalized in our gut-reactions.

So while it's obviously important to outwardly appreciate, respect, and protect all species, I think the instinctual interests and affinities and emotional and psychological responses that we have towards other mammals and certain other creatures make a lot of sense, and are ultimately the key to why we want to protect the Earth and its inhabitants as they are now, and not simply devise ways to survive without them.

@Christine Dell'Amore Again...it is not just that they are cute or big. It is because mammals are more likely to have just one subspecies. Or at least fewer. There are hundreds of different types of snakes. So if we lose a few subspecies of snakes, there will still be plenty more left. But if we lose tigers or elephants, then we have no more tigers or elephants at all.

@Judy Bierman-Rudolph Your premise is invalid. You assume we are the chosen species and our consciousness "higher" instead of "different" which is exactly why everything is dying including us. Your Ultimate Imaginary Friend was created by humans to give ourselves a superior medal. But there is no superior being as there is no inferior being. There is only BEING, the colossal equality of existence.

@Judy Bierman-Rudolph Strange...you are SO religious that you actually think that God is such a prick that he will send you to hell simply for spelling his name, but you don't know the Bible enough to know that religion teaches us that animals were put on the earth specifically FOR humans.

@charlie linebarger@Sarah Bexell It is NOT the number of humans erp se that automatically endangers anything. It is the way we ACT. We could live much more like agricultural/hunter-gatherers at 10 billion and still not wipe out the numbers of species we are at almost 7 billion, which began before we were at 4 billion. It is because we see everything we kill, and allow to die because of our anti-'other' bad habits, as food or nuisance.

@John Kalawak@Christa Witvrouwen I suggest you have a bit more of an open mind. Yes, each species, including ourselves, are governed by competition laws but that doesn't give us the right to drive other species to mass extinction. We have morals and our actions do have an effect on the natural environment. If you think that our actions as a species isn't responsible for the decline of other species, then that is pure ignorance. Each species has a role to play in each ecosystem they live in. The complete ecosystem goes onto to support the top mammal / predator i.e us, the human race. By driving species to extinction or neglecting the plight of other species, we neglect the environment that supports our own health. We need other species to maintain the ecosystems we rely on t survive/

@John Kalawak@Christa Witvrouwen No, we have created the conditions for this current mass extinction. btw we ARE nature, just as much as non-human nature is. This process is as natural as our attempts to stop it would be, if we had the intelligence. The only reason it's happening is because we don't.